Familial dysautonomia (FD) is a hereditary sensory and autonomic neuropathy that is caused by a splice mutation in the IKBKAP gene. The mutation results in variable skipping of exon 20 in IKBKAP mRNA, which leads to a tissue-specific reduction of IKAP protein. Analysis of tissues from FD patients shows significantly more exon-skipping in neuronal tissue, and therefore lower IKAP levels. IKAP is a member of the human Elongator complex, which is required for efficient transcriptional elongation of a subset of genes. Despite the fact that FD is recessive, we have shown that patients retain the capacity to make both normal mRNA and protein. This discovery offers an exciting, direct approach towards the development of therapies aimed at increasing levels of cellular IKAP via splicing modification. As part of the NINDS-sponsored Neurodegeneration Drug Screening Consortium, we found that treatment of cultured FD cells with kinetin, a plant cytokinin, enhances exon-20-inclusion and dramatically increases the amount of wild-type IKBKAP mRNA and IKAP protein in FD cells. This compound has remarkable efficacy and can restore normal IKAP protein levels in patient cells within one week in culture. We have demonstrated kinetin's ability to alter IKBKAP splicing using minigene assays in a variety of cell types, as well as in human cells. More recently, we have shown in vivo efficacy in both transgenic mice and in human FD carriers. Despite substantial investment by the Dysautonomia Foundation in developing kinetin as a potential treatment for FD, the road to the clinic has been slow, and we are still working with the originally identified compound. We have recently generated some promising SAR (structure and activity relationship) data showing that the activity of the lead compound kinetin can be improved. It is crucial that chemical optimization be performed in order to improve the potency and activity of kinetin, and time is of the essence. Despite the fact that FD is a developmental disorder, patients are plagued by continued, drastic neuronal degeneration throughout life. Effectively increasing IKAP levels early in life may support neuronal survival and prevent or delay the debilitating gait and sensory and cognitive decline seen in patients as they age. The Blueprint Neurotherapeutics Network offers a unique opportunity for drug development that will provide access to resources that are currently out of reach.

Public Health Relevance

Familial dysautonomia is a severe neurodevelopmental disease that is caused by a mutation in the IKBKAP gene. This mutations leads to reduced protein expression in all tissues, but this reduction is variable and is most severe in neuronal tissue. We have identified a compound, kinetin, that can increase IKAP protein in patient cells, and the goal of this proposal is to chemically optimize the potency and activity of kinetin in orde to develop an effective treatment for FD.